Regulated floating output

ABSTRACT

A dual output voltage regulator supplying regulated voltages of opposite polarity regulates the first output by a differential error detecting circuit referenced to a constant voltage. The other regulated output of opposite polarity is referenced directly to the first output and is controlled by the second differential error detecting circuit, without being influenced by regulation of the first output.

United States Patent 1 Fendrich, Jr.

11] 3,745,363 July 10, 1973 REGULATED FLOATING OUTPUT [75] Inventor: Charles Nelson Fendrich, Jr.,

Elizabethtown, Pa.

[73] Assignee: AMP Incorporated, Harrisburg, Pa.

[22] Filed: Aug. 12, 1971 [21] App]. No.: 171,050

52 us. c1. 307 34, 323 22 T, 323/25 51 int. c1. G05f 1/56 Field of Search 307/15, 24, 31, 32, 307/34, 44, 5s, 6O, 82; 321/19, 27 R; 323/20,

[56] References Cited UNITED STATES PATENTS 11/1956 Liguori 323/23 X Gamble 323/23 X CONVERTER i 2 3,376,410 4/1968 Lundin 323/22 T 3,391,284 7/1968 Stupar 3,571,604 3/1971 La Porta et a] 323/23 X Primary Examiner-A. D. Pellinen Attorney-William J. Keating. Gerald K. Kit11..lohn R. Flanagan and Allan B. Osborne [5 7 ABSTRACT A dual output voltage regulator supplying regulated voltages of opposite polarity regulates the first output by a differential error detecting circuit referenced to a constant voltage. The other regulated output of opposite polarity is referenced directly to the first output and is controlled by the second differential error detecting circuit, without being influenced by regulation of the first output.

5 Claims, 2 Drawing Figures Patented Ju y 10, 1973 I 3,745,363

ZSheets-Sheet 1 lA/VE/VTOR CHARLES NELSON FENDRICH Jr.

BY GERALD K. KITA Patented July 10, 1973 2 Sheets-Sheet 2 N mmPmm ZOo mmPmm zOo REGULATED FLOATING OUTPUT The present invention relates to a dual output voltage regulator, and more particularly, to a dual output voltage regulator supplying regulated voltages of opposite polarity, wherein one of the outputs is referenced to the other. A feature of the present invention resides in the improvement over a prior art concept of supplying a separate regulating circuit for controlling each of a desired plurality of regulated outputs. The invention eliminates the need for separate comparator circuits one of which is referenced to high voltage. Instead, the invention allows independent regulation of dual opposite polarity output voltages referenced to each other using regulators referenced to ground potential.

An object of the present invention is to provide a dual regulated output using two sensing strings for a differential error detecting circuit which regulates a first output for load and line changes independently of the other regulated output used as a reference for the first output.

Other objects and many attendant advantages of the present invention will become apparent upon perusal of the following detailed description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic of the preferred embodiment of a dual output voltage regulator according to the present invention; and

FIGv 2 is a schematic of the details of a comparator circuit portion of the preferred embodiment illustrated in FIG. 1.

With more particular reference to the drawings, there is shown in FIG. 1 a dual output voltage regulator generally indicated at 1 and including a pair of input terminals 2 and 4 for operative coupling to a DC input (not shown). The input terminal 4 is referenced to ground at 6 through an electrical path 8 and also to an input side of a converter, indicated in the legend as converter 2. The input terminal 2 is coupled to a collector of a pass transistor Q by a lead line 10, with the emitter of the pass transistor coupled to the input lead 11 of a converter, generally indicated in the schematic by converter 1. In addition, the input terminal 2 is connected by a lead 12 to the collector of a second pass transistor Q with the emitter of the second pass transistor coupled to an input lead 14 of the converter 2.

Input terminal 4 is coupled through lead line 8 to the input lead 9 of the converter 2. In addition, the input terminal 4 is connected to the input lead of the converter l.

The output of converter 2 is supplied to a first output terminal 16 referenced to ground at 18 and also to an output terminal 20 of negative polarity, thereby providing an output voltage V at the output terminals 16 and 20. The negative polarity of output supplied to the terminal 20 also supplies a sampling signal via a lead 22 between the terminal 20 and a comparator 24. An output of the comparator (V is supplied to an output terminal 26 in a manner to be hereinafter described in detail. Such output is supplied to a buffer amplifier indicated schematically at 28, which buffer amplifier is referenced to ground at 30 with the output of the buffer amplifier being supplied to the base of the pass transistor Qpz to bias the transistor to a more or less conducting state as required to control the input voltage to the converter 2 and thereby regulate the output V The output of converter 1 is connected by a lead 32 to the terminal 20, thereby referencing the output V of the converter 1 to the output V of converter 2. In addition, the output side of converter 1 is provided with an output terminal 34 which supplies a positive polarity regulated voltage as output V between the terminals 34 and 20 as indicated in FIG. 1. In addition, the positive polarity output from the terminal 34 is supplied over a lead 36 to provide a positive polarity sampling signal to the comparator 24. The comparator provides an output signal V over the output terminal 38, in a manner to be hereinafter described in detail. Such output signal V is supplied to a buffer amplifier indicated schematically at 40 that is referenced to ground at 42. The output of the buffer amplifier 40 is supplied to the base of the pass transistor Qp to render the transistor more or less conducting as required to control input voltage to the converter 1 and to accordingly control the output V It is understood that the pass transistors Q and Qpz may be replaced by any suitable controlled gating devices for regulating the voltage supplied from the input terminals 2 and 4 to the respective converters, 1 and 2. It is further understood that the converter 1 and the converter 2 may each comprise a transformer, the secondary windings of which are directionally coupled to provide the required polarity outputs V and V at the terminals 34 and 20. Any other suitable equivalent circuitry may be substituted for the converters.

With more particular reference to FIG. 2, the details of the comparator, generally shown at 24 in FIG. 2, will be described in detail. The comparator 24 includes a pair of input terminals 44 and 46 for receiving a constant voltage from reference source V of positive 20 volts magnitude. The positive side of the reference voltage V is supplied over a lead 48 through a resistor R, to the collector of a transistor Q and also over the lead 48 to the collector of another transistor Q The emitters of transistors Q and Q are coupled together to provide a differential error detecting circuit referenced to ground at 50 through a resistor 52. The output terminal 38 is connected at the junction of the resistor R and the collector of the transistor Q to supply the comparator output voltage V which is supplied to the base of the pass transistor Qm as shown in FIG. 1.

The input lead 48 additionally supplies the positive polarity of the reference voltage V to a Zener diode 54 referenced to ground at 50 through a resistor 56. The Zener diode insures a constant voltage V equal to 6 volts across the base of a transistor Q The emitters of transistors Q and Q, are coupled together to form a differential error detecting circuit referenced to ground at 50 through a resistor 58. Asshown in FIG. 2, the input to the collector of the transistor 0; is supplied through a resistor R with the output terminal 26 connected at the intersection of the resistor R, and the collector of transistor Q: for supplying the comparator ouput voltage V to the pass transistor Qpz as shown in FIG. I. The base of transistor O is connected through a sensing string or series of resistors 60, 62 and- 64 to the lead 36. The base of transistor 0;, is provided with a potentiometer connection 66 adjustably connected to the resistor 62. As shown in FIG. 2, the resistor and a portion of the resistor 62 on one side of the potentiometer connection 66 cooperate to form a resistance value indicated at R The resistor 64 together with a portion of the resistor 62 on the other side of the potentiometer connection 66 cooperate to form a resistance value indicated schematically at R Yet with reference to FIG. 2, the collector of transistor Q is connected through a sensing string or series of resistors 66, 68, 70, 72 and 74 to the lead 22. The base of transistor Q is provided with a potentiometer connection 76 to the resistor 68. The base of transistor Q. is connected by a potentiometer connection 78 to the resistor 72. Together the resistors 74, 72, 70 and a portion of the resistor 68 on one side of the potentiometer connection 76 comprise a resistance value schematically indicated at R Together the resistor 66 and the portion of the resistor 68 on the other side of the potentiometer connection 76 comprise a resistance value schematically indicated at R Together the resistors 66, 68, 70 and a portion of the resistor 72 on one side of the potentiometer connection 78 comprise a resistance value schematically indicated in the Figure at R,.

In operation, with V referenced to ground, if V becomes larger in magnitude, i.e. more negative, the current i increases in the direction shown. The voltage drop across resistance value R increases thereby rendering the transistor Q less conductive. The corresponding transistor Q of the differential error detecting circuit will thus be rendered proportionately more conductive. With the terminal 26 at the junction of the resistor R, and the collector of the transistor Q the output V will become more negative. As shown in FIG. 1, the output V is supplied through the buffer amplifier 28 to render the transistor Q less conductive and thereby reduce the magnitude of voltage supplied through the converter 2 to the output terminals 16 and 20, thereby regulating the output over the terminals l6 and 20 and counteracting the tendency of current i to increase in magnitude.

To regulate V for line or load change, assume that V remains constant. If V increases, for example, i will decrease thereby decreasing the voltage drop across R and the base voltage of Q will increase. Since V is constant, i remains constant and the voltage on the base of (2., remains constant. The voltage V will become more negative and consequently biases the pass transistor QPl toward a non-conducting state thereby counteracting the tendency of V to increase.

To make V5 independent of changes in V if for example, V increases in magnitude, the change in voltage due to increase in i across R must equal the voltage change across R in order to prevent any changes in output of Q and hence keep output V constant. For this to occur, the following equations must be satisfied:

But, R R

so, R R =R,

thus, 02 x/ 2) z Similarly, V +i,R (RJR V V (R /R if we choose R /R, R /R the", 02 s/ a) z s/ a) 02 01) 0 z VOI a/ a) Although preferred embodiments of the present invention have been described in detail, other modifications and embodiments of the present invention which would be obvious to an artisan having ordinary skill in the art are intended to be covered in the spirit and scope of the appended claims.

What is claimed is: l. A regulated dual output voltage supply of opposite polarity comprising,

a pair of voltage input terminals one of which is grounded, first means connected to said input terminals for producing across a pair of ungrounded output terminals an ungrounded output voltage, second means connected to said input terminals for producing an output voltage across one of said ungrounded terminals and ground, said output voltages thus having a common ungrounded terminal, means for regulating both said output voltages comprising, first detecting means for detecting changes from a predetermined voltage in the voltage across the ungrounded terminals to produce a first error signal, means responsive to the first error signal for varying the input to said first means for maintaining a constant ungrounded output voltage, second detector means including a portion of the first detector means for detecting changes in the output voltage between said one ungrounded terminal and ground to produce a second error signal,

and means responsive to said second'error signal for I varying the input to said second means for maintaining a constant voltage relative to ground.

2. A regulated dual output voltage supply according to claim 1 wherein said second means provides an output voltage which is greater than said first ungrounded output voltage.

3. A regulated dual output voltage supply according to claim 1 wherein the means for detecting changes in the grounded and ungrounded voltage outputs comprises a pair of comparator circuits each comparing the respective output voltage with agrounded reference voltage,

said reference voltage being supplied by a grounded source which is separate and independent from the output voltages and is common to both comparator circuits.

4. A regulated dual output voltage supply according to claim 3 including means for renderingchanges in the output voltage between the common terminal and ground ineffective to change the output voltage across the ungrounded terminals.

5. A regulated dual output voltage supply according to claim 3 in which the means fordete'cting changes in the output voltages for producing error voltages comprises,

a first resistance connected between the referencesupply and the common ungrounded terminal,

a first tap on said first resistance for applying the voltage thereon to one comparator circuit for comparing it directly with the reference voltage,

a second tap on the resistance,

the other'ungrounded terminal of the .ungrounded output voltage being connected to the reference voltage through a second resistance,

a second tap on the second resistance connected to the other comparator circuit for comparison with the voltage on the second tap of the first resistance. 

1. A regulated dual output voltage supply of opposite polarity comprising, a pair of voltage input terminals one of which is grounded, first means connected to said input terminals for producing across a pair of ungrounded output terminals an ungrounded output voltage, second means connected to said input terminals for producing an output voltage across one of said ungrounded terminals and ground, said output voltages thus having a common ungrounded terminal, means for regulating both said output voltages comprising, first detecting means for detecting changes from a predetermined voltage in the voltage across the ungrounded terminals to produce a first error signal, means responsive to the first error signal for varying the input to said first means for maintaining a constant ungrounded output voltage, second detector means including a portion of the first detector means for detecting changes in the output voltage between said one ungrounded terminal and ground to produce a second error signal, and means responsive to said second error signal for varying the input to said second means for maintaining a constant voltage relative to ground.
 2. A regulated dual output voltage supply according to claim 1 wherein said second means provides an output voltage which is greater than said first ungrounded output voltage.
 3. A regulated dual output voltage supply according to claim 1 wherein the means for detecting changes in the grounded and ungrounded voltage outputs comprises a pair of comparator circuits each comparing the respective output voltage with agrounded reference voltage, said reference voltage being supplied by a grounded source which is separate and independent from the output voltages and is common to both comparator circuits.
 4. A regulated dual output voltage supply according to claim 3 including means for rendering changes in the output voltage between the common terminal and ground ineffective to change the output voltage across the ungrounded terminals.
 5. A regulated dual output voltage supply according to claim 3 in which the means for detecting changes in the output voltages for producing error voltages comprises, a first resistance connected between the reference supply and the common ungrounded terminal, a first tap on said first resistance for applying the voltage thereon to one comparator circuit for comparing it directly with the reference voltage, a second tap on the resistance, the other ungrounded terminal of the ungrounded output voltage being connected to the reference voltage through a second resistance, a second tap on the second resistance connected to the other comparator circuit for comparison with the voltage on the second tap of the first resistance. 